Crosslinking resin composition

ABSTRACT

Disclosed is a crosslinking resin composition comprising: (A) a carboxyl group-containing resin as a main agent, having a number average molecular weight of from 1,000 to 40,000 and an acid value of from 10 to 400 mg KOH/g; (B) a cyclic or chain silicone compound as a curing agent, having a number average molecular weight of from 350 to 8,000 and containing at least two epoxy groups in one molecule thereof, wherein the silicone compound is free of a silanol group, a hydrolyzable silyl group and a vinyl polymer structure, and wherein the silicone compound has a siloxy group-containing skeleton; and (C) a medium. The crosslinking resin composition of the present invention not only exhibits excellent storage stability, but is also capable of providing, upon being crosslinked, a cured resin having excellent gloss, weatherability, acid resistance, solvent resistance, water repellency and stain resistance. Therefore, the crosslinking resin composition can be advantageously used for providing various coating compositions, such as paints, and sealants.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a novel crosslinking resin composition.More particularly, the present invention is concerned with a novelcrosslinking resin composition comprising: a carboxyl group-containingresin as a main agent; a cyclic or chain silicone compound as a curingagent, which contains at least two epoxy groups in one molecule thereofand which is free of a silanol group, a hydrolyzable silyl group and avinyl polymer structure; and a medium. The crosslinking resincomposition not only exhibits excellent storage stability, but is alsocapable of providing, upon being crosslinked, a cured resin havingexcellent weatherability, acid resistance, solvent resistance, stainresistance and surface smoothness. Therefore, the crosslinking resincomposition of the present invention can be advantageously used forproviding coating compositions, such as paints, sealants and the like.

2. Prior Art

Some vinyl polymers having alkoxysilyl groups at the terminals thereofand/or in side chains thereof and coating compositions containing thesame are disclosed in, for example, Unexamined Japanese PatentApplication Laid-Open Specification Nos. 54-36395 (corresponding to U.S.Pat. No. 4,334,036), 54-40893 and 54-123192. These vinyl polymers haveexcellent weatherability and acid resistance. However, these vinylpolymers have a problem with their stability. In use, these vinylpolymers having alkoxy silyl groups are used as a main agent incombination with a curing catalyst, and the curing of the vinyl polymeris performed by crosslinking through hydrolysis condensation of thealkoxy silyl groups with the water contained in the air. Therefore, whenthe vinyl polymer contains water as a contaminant, the storage stabilityof the vinyl polymer is likely to be lower. Further, when this vinylpolymer is formulated into a paint by using a pigment, the storagestability of the paint may be adversely affected by the water containedin the pigment.

U.S. Pat. No. 5,210,150 discloses a melt-moldable, moisture-curingadhesive using a reaction product of a vinyl resin having carboxylicacid groups with an epoxy silane. As examples of epoxy silanes,glycidoxypropyltrimethoxysilane andβ-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are described. These epoxysilanes have only one epoxy group in one molecule thereof, so that acuring reaction does not proceed between such epoxy silanes and carboxylgroups. Further, since the epoxy silane capable of reacting with a vinylresin having carboxylic acid groups contains hydrolyzable methoxysilylgroups, the above-mentioned reaction product inherently has poor storagestability. Furthermore, when the above-mentioned reaction product isformulated into a paint by using a pigment, the storage stability of thepaint may be adversely affected by the water contained in the pigment.

British Patent No. 2247461 (corresponding to Unexamined Japanese PatentApplication Laid-Open Specification No. 4-110350) discloses a curingresin comprising: (I) a polysiloxane resin comprising a reaction productof (A) a silane compound having at least one hydroxyl group and/orhydrolyzable group, which is directly bonded to the silicon atomthereof, with (B) a silane compound having at least one hydroxyl groupand/or hydrolyzable group which is directly bonded to the silicon atomthereof and at least one epoxy group (thus, on the average, thepolysiloxane has, per molecule thereof, at least one epoxy group and atleast two hydroxyl groups and/or at least two hydrolyzable groups whichare bonded to the silicon atom thereof); and (II) a resin havinghydroxyl groups and carboxyl groups. The curing resin proposed in theabove British patent has problems in that a silanol group which isformed by the above-mentioned direct bonding of the hydroxyl group tothe silicon atom is highly susceptible to condensation. The resultingresin having such a silanol group has poor stability and, therefore,must be stored and handled with great care. The hydrolyzable groupcontained in the resin inherently has an adverse influence on thestability of the resin, although the susceptibility of the hydrolyzablegroup to hydrolysis and condensation is lower than that of the silanolgroup.

SUMMARY OF THE INVENTION

In these situations, the present inventors have made extensive andintensive studies with a view toward developing a crosslinking resincomposition which not only has good storage stability and excellentcurability, but also is capable of providing a cured resin stillexhibiting excellent weatherability, excellent acid resistance and thelike, which are characteristics of a cured silicone resin. As a result,it has been unexpectedly found that it is possible to obtain such acrosslinking resin composition having such excellent properties orcharacteristics by combining a specific, carboxyl group-containing resinhaving no highly hydrolyzable silyl group (alkoxysilyl group) thereinwith a specific compound containing Si atoms and at least two epoxygroups in one molecule thereof. The present invention has beencompleted, based on this novel finding.

According to the present invention, there is provided a novelcrosslinking resin composition comprising:

(A) a carboxyl group-containing resin as a main agent, having a numberaverage molecular weight of from 1,000 to 40,000 and an acid value offrom 10 to 400 mg KOH/g;

(B) a cyclic or chain silicone compound as a curing agent, having anumber average molecular weight of from 350 to 8,000 and containing atleast two epoxy groups in one molecule thereof, wherein the siliconecompound is free of a silanol group, a hydrolyzable silyl group and avinyl polymer structure, and wherein the silicone compound has a siloxygroup-containing skeleton represented by a formula selected from thegroup consisting of the following formulae (I) and (II): ##STR1##wherein n is an integer of from 3 to 20, and ##STR2## (C) a medium.

DETAILED DESCRIPTION OF THE INVENTION

In the present invention it is preferred that the resin as component (A)be at least one resin selected from a acrylic resin, a polyester resinand a fluorine-containing resin.

The resin component (A) has a number average molecular weight of 1,000to 40,000, preferably 2,000 to 40,000. When the number average molecularweight of the resin is less than 1,000, the properties of a cured resinobtained from the crosslinking resin composition become poor. When themolecular weight is more than 40,000, the viscosity of the resin isexcessively high, so that it becomes difficult to handle the resin. Thenumber average molecular weight of the resin can be measured by gelpermeation chromatography (GPC), as described below.

The resin (A) has an acid value of 10 to 400 mg KOH/g, preferably 20 to300 mg KOH/g. When the acid value is less than 10 mg KOH/g, it becomesdifficult for the resin composition to be cured satisfactorily, so thata cured resin having satisfactory properties cannot be obtained. Whenthe acid value is more than 400 mg KOH/g, the ratio of carboxyl groupsnot participating in the crosslinking reaction becomes large, or thecrosslink density becomes excessively high, so that, not only do theproperties of a cured resin obtained from the resin composition becomepoor, but the viscosity of the resin itself also becomes excessivelyhigh, so that the solvent usable for the resin is limited. The acidvalue of the resin is measured according to the method of ASTM-1638.

The resin component (A) may contain hydroxyl groups therein. Thehydroxyl group reacts with the epoxy groups of the silicone compoundcomponent (B), thereby taking part in the crosslink-curing. Furthermore,when the resin contains hydroxyl groups, there are advantages in that,when the resin composition of the present invention is formulated into apaint by using a pigment, not only can the pigment be uniformlydispersed in the resin composition, but also excellent adhesion of thepaint to a substrate is achieved. When the resin component (A) containshydroxyl groups, it is preferred that the resin contain hydroxyl groupsin the range of not more than 300 mg KOH/g in terms of the hydroxylvalue of the resin. When the hydroxyl value is more than 300 mg KOH/g,the properties of a cured resin obtained from the resin compositionbecome poor. The hydroxyl value is more preferably not more than 200 mgKOH/g. Further, it is preferred that the sum of the respective amountsof carboxyl groups and hydroxyl groups in the resin is not more than 400mg KOH/g in terms of the sum of the acid value and the hydroxyl value ofthe resin. The hydroxyl value of the resin can be measured according tothe method of ASTM-1638.

In view of the intended main use of the crosslinking resin compositionof the present invention as a material for coating compositions, paints,sealants and the like which can provide ultimate cured resins havinghigh durability, it is preferred that the base resin for the carboxylgroup-containing resin component (A) be selected from an acrylic resin,a polyester resin and a fluorine-containing resin. These resins can beused individually or in combination.

The carboxyl-containing acrylic resin usable as component (A) can beprepared by copolymerizing an acrylic monomer or a vinyl monomer with acarboxyl-containing comonomer, such as acrylic acid, methacrylic acidand maleic acid. Examples of acrylic monomers and other vinyl monomersinclude methyl (meth)acrylate, ethyl (meth)acrylate, propyl(meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate,glycidyl (meth)acrylate, maleic anhydride, styrene and acrylonitrile.When it is desired to introduce hydroxyl groups into the acrylic resin,a hydroxyl-containing monomer is used as a comonomer in thecopolymerization for obtaining an acrylic resin. Examples ofhydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate,2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate and3-hydroxybutyl (meth)acrylate.

The acrylic resin can be produced by copolymerizing a mixture of theabove-mentioned vinyl monomers in the presence or absence of a solventby using a polymerization initiator or ionizing radiation as a means forinitiating the polymerization. In the copolymerization, the addition ofa vinyl monomer to the reaction system can be conducted in a batchwiseand/or continuous manner, depending on the copolymerizability and thereactivity (such as, heat generation capacity) of the vinyl monomer.

As the polymerization initiator, a water-soluble or oil-solublepolymerization initiator can be appropriately selected, depending on themode of the polymerization process, the properties of the initiator andthe like.

Examples of oil-soluble initiators include azo compounds, such asazobisisobutyronitrile, 2-2'-azobis(2,4-dimethyl valeronitrile);peroxyesters, such as t-butyl peroxypivalate and t-butylperoxyisobutylate; diacyl peroxides, such as octanoyl peroxide, lauroylperoxide and benzoyl peroxide; dialkyl peroxydicarbonates, such asdiisopropyl peroxydicarbonate; and dialkyl peroxides.

Examples of water-soluble initiators include persulfates, such aspotassium persulfate, hydrogen peroxide and redox initiators comprisinga combination of a persulfate or hydrogen peroxide with a reducingagent, such as sodium hydrogensulfite or thiosulfate; inorganicinitiators comprising a combination of a persulfate or hydrogen peroxidewith a small amount of iron, a ferrous salt, silver nitrate and thelike; and organic initiators, such as dibasic acid peroxides (e.g.,disuccinic acid peroxide, diglutaric acid peroxide, monosuccinic acidperoxide) and a dibasic acid salt of azobisisobutylamizine.

The amount of the initiator is selected depending on the type of theinitiator, the copolymerization reaction conditions and the like. Theamount of the initiator is generally in the range of from 0.005 to 8% byweight, preferably from 0.05 to 5% by weight, based on the total weightof the monomers used.

The polymerization method is not specifically limited by the foregoingexamples, and various methods, such as bulk polymerization, suspensionpolymerization, emulsion polymerization and solution polymerization, canbe employed. From the viewpoint of the stability of the polymerizationoperation, solution polymerization using an organic solvent ispreferred.

Examples of solvents include aromatic hydrocarbons, such as benzene,toluene and xylene and the like; esters, such as ethyl acetate, propylacetate, butyl acetate, amyl acetate, 2-ethylbutyl acetate, methoxybutylacetate, methylisoamyl acetate, 2-ethylhexyl acetate, cyclohexylacetate, methylcyclohexyl acetate, methyl propionate, ethyl propionate,propyl propionate, butyl propionate, isoamyl propionate and the like;alcohols, such as ethanol, propanol, butanol, pentanol and the like;ketones, such as acetone, methyl ethyl ketone, diethyl ketone, methylpropyl ketone, methyl butyl ketone, methyl amyl ketone, methyl isobutylketone and the like; ethers, such as dipropyl ether, dibutyl ether,dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether,ethylene glycol dipropyl ether, ethylene glycol dibutyl ether,diethylene glycol dimethyl ether, diethylene glycol diethyl ether,ethylene glycol monopropyl ether, ethylene glycol monobutyl ether,ethylene glycol monoethyl acetate, diethylene glycol monomethyl ether,diethylene glycol monoethyl ether, ethylene glycol monoacetate, ethyleneglycol diacetate, propylene glycol monomethyl ether, propylene glycolmonoethyl ether, propylene glycol monopropyl ether, propylene glycolmonobutyl ether, dipropylene glycol monomethyl ether, propylene glycolmonomethyl ether acetate, propylene glycol dimethyl ether, propyleneglycol diethyl ether, dipropylene glycol monoethyl ether and the like.Chain transfer agents, such as butyl mercaptan, dodecyl mercaptan, and ahalogenated hydrocarbon, can also be used as the solvent.

The polymerization temperature is varied, depending on the type andamount of the initiator used, and can be selected in the range of fromroom temperature to 150° C. The molecular weight of a copolymer to besynthesized can be controlled by selecting the type and amount of theinitiator and the polymerization temperature.

Examples of polyester resins which can be used as component (A) includeconventional polyester resins obtained from an acid and an alcohol.Examples of acids include phthalic anhydride, phthalic acid,tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic acid,succinic acid, adipic acid, trimellitic acid anhydride and the like.Examples of alcohols include ethylene glycol, propylene glycol, butanediol, trimethylolpropane, glycerin and the like. The acid value of thepolyester resin can be controlled by regulating the ratio of thepolybasic acid to the polyhydric alcohol.

The carboxyl group-containing fluoro-resin usable as component (A) canbe prepared by copolymerizing a fluoro-monomer, such astetrafluoroethylene, chlorotrifluoroethylene, difluoroethylene,trifluorochloroethylene, dichlorotrifluoropropylene and the like, with acomonomer, such as acrylic acid, methacrylic acid and maleic acid thelike. When it is desired to introduce a hydroxyl group into thefluoro-resin, the introduction can be performed by using a hydroxylgroup-containing monomer. Examples of hydroxyl group-containing monomersinclude vinyl alcohol, allyl alcohol, allyloxyethanol,4-hydroxybutylvinyl ether and the like.

The silicone compound component (B) is a cyclic or chain siliconecompound which contains at least two epoxy groups in one moleculethereof on the average, which epoxy group is capable of reacting withthe carboxyl group of component (A) and with an optional hydroxy groupof component (A). The silicone compound (B) is free of a silanol group,a hydrolyzable silyl group and a vinyl polymer structure, and has asiloxy group-containing skeleton represented by a formula selected fromthe group consisting of the following formulae (I) and (II): ##STR3##wherein n is an integer of from 3 to 20, and ##STR4##

The number average molecular weight of the silicone compound (B) is from350 to 8,000, preferably from 360 to 5,000, more preferably from 450 to3,000. The number average molecular weight is measured by GPC.

When a vinyl polymer containing an epoxy group and a terminal or pendanthydrolyzable silyl group is employed in place of the above-mentionedsilicone compound (B), the resin composition is unstable due to thepresence of the hydrolyzable silyl group in the vinyl polymer. Further,the vinyl polymer is difficult to handle because it has a high molecularweight.

When a conventional, epoxy group-containing silane coupling reagent isemployed in place of the silicone compound (B), satisfactory curing ofthe resin composition cannot be achieved, because the conventionalsilane coupling reagent has only one epoxy group per molecule on theaverage and this amount of epoxy groups is too small to satisfactorilycure the resin composition by the reaction thereof with carboxyl groupsof resin (A). Further, some silane coupling reagents have a low boilingpoint and, therefore, the use of the silane coupling agent has adisadvantage in that, when curing with such a silane coupling reagent isconducted at high temperatures, the coupling reagent is volatilizedbefore a crosslinking reaction occurs, so that the silane couplingreagent cannot be fully and effectively utilized.

When the silicone compound component (B) contains a silanol group or ahydrolyzable silyl group, the resin composition has poor stability. Onthe other hand, when the number of epoxy groups in one molecule of thesilicone compound component (B) is less than two on the average, asatisfactory curing of the resin composition cannot be achieved, so thatthe mechanical properties of the ultimate cured resin composition arepoor.

When the silicone compound (B) has no functional groups capable ofreacting with the carboxyl group and optional hydroxyl group of theresin (A) other than the epoxy groups, it is preferred that component(B) contain at least 2.1 epoxy groups per molecule thereof on theaverage.

The silicone compound component (B) is not specifically limited as longas the silicone compound is a cyclic or chain silicone compoundcontaining at least two epoxy groups per molecule thereof on theaverage, wherein the silicone compound is free of a silanol group, ahydrolyzable silyl group and a vinyl polymer structure, and wherein thesilicone compound has a siloxy group-containing skeleton represented bya formula selected from the group consisting of the formulae (I) and(II). However, the number average molecular weight of the siliconcompound (B) is generally in the range of from 350 to 8,000. A siliconecompound (B) having a number average molecular weight of less than 350is difficult to synthesize and is not easily commercially available.When the number average molecular weight of the silicone compound ascomponent (B) is larger than 8,000, it becomes difficult to handlecomponent (B) because of its high viscosity. Further, in this case, aproblem also arises in that the reactivity between the carboxyl group ofcomponent (A) (hereinafter, occasionally referred to as " functionalgroup A!") and the epoxy group of component (B) (hereinafter,occasionally referred to as " functional group B!") is lowered.

The silicone compound component (B) may comprise either a single type ofsilicone compound or a mixture of two or more types of siliconecompounds.

Specific examples of component (B) include a cyclic silicone compoundrepresented by the following formula (III): ##STR5## wherein m is aninteger of from 3 to 16, each R¹ independently represents a C₁ -C₁₀alkyl group and each Ep independently represents a group represented bya formula selected from the group consisting of the following formulae(1), (2) and (3): ##STR6## wherein j is an integer of from 2 to 6; and achain silicone compound represented by the following formula (IV):##STR7## wherein each of R² to R⁸ independently represents a C₁ -C₁₀alkyl group, each Ep is as defined above for formula (III) and r is aninteger of from 3 to 16.

These compounds may be employed individually or in combination.

A further example of the silicone compound component (B) is a siliconecompound obtained by a hydrosilylation reaction of a Si--H-containingsilane compound with an epoxy group-containing compound having acarbon-carbon double bond, using a platinum catalyst or the like,wherein the Si--H-containing silane compound is represented by a formulaselected from the group consisting of the following formulae (V), (VI)and (VII): ##STR8## wherein each Y independently represents a hydrogenatom or a C₁ -C₁₀ alkyl group, with the proviso that at least two Ys inone molecule of the Si--H-containing silane compound are hydrogen atoms,and q is an integer of from 2 to 10; ##STR9## wherein each Yindependently represents a hydrogen atom or a C₁ -C₁₀ alkyl group, withthe proviso that at least two Ys in one molecule of the Si--H-containingsilane compound are hydrogen atoms, and p is an integer of from 3 to 20;and ##STR10## wherein each Y independently represents a hydrogen atom ora C₁ -C₁₀ alkyl group, with the proviso that at least two Ys in onemolecule of the Si--H-containing silane compound are hydrogen atoms, ands is an integer of from 3 to 16.

The Si--H-containing silane compound may contain both of the structuralunits of formulae (V) and (VI) above.

Examples of epoxy group-containing compounds having a carbon-carbondouble bond include allyl glycidyl ether, 5-epoxy-1-hexene, vinylcyclohexene oxide and limonene oxide.

Alternatively, silicone compound (B) can also be obtained by hydrolyzinga bifunctional silane, such as methyldichlorosilane, represented by theformula RHSiX₂ (wherein R represents a C₁ -C₁₀ alkyl group and Xrepresents a halogen atom or a hydrolyzable group) to obtain a cyclicsilane compound; and conducting a hydrosilylation reaction of theobtained cyclic silane compound with an epoxy group-containing compoundhaving a carbon-carbon double bond in the presence of, for example, aplatinum catalyst.

In conducting the hydrosilylation reaction of a Si--H-containing silanecompound with an epoxy group-containing compound having a carbon-carbondouble bond for introducing epoxy groups into the silane compound, othercompounds having a carbon-carbon double bond may also be used inaddition to the epoxy group-containing compound having a carbon-carbondouble bond, as long as a silicone compound containing at least twoepoxy groups per molecule on the average can be obtained.

Examples of other compounds having a carbon--carbon double bond includeolefins, such as 1-hexene, 1-heptene, 1-octene, isobutene,5-methyl-1-butene and cyclohexene; allyl esters, such as allyl acetate,allyl propionate and allyl 2-ethylhexanoate; allyl ethers, such as allylmethyl ether, allyl ethyl ether, allyl propyl ether, allyl hexyl ether,allyl cyclohexyl ether and allyl-2-ethylhexyl ether; (meth)acrylates,such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylateand phenyl (meth)acrylate; carboxylic vinyl esters, such as vinylacetate, vinyl propionate, vinyl butyrate, vinyl stearate and vinylbenzoate; vinyl ethers, such as methyl vinyl ether, ethyl vinyl ether,butyl vinyl ether, isobutyl vinyl ether and cyclohexyl vinyl ether;(meth)acrylonitrile; styrene; and crotonic ester.

Silicone compound (B) can also be obtained by a hydrosilyation reactionof a Si--H-containing silicone compound, such as1,1,1,3,5,7,7,7-octamethyltetradisiloxane,1,3,5,7-tetramethylcyclotetrasiloxane and1,3,5,7,9-pentamethylcyclopentasiloxane, with an epoxy group-containingcompound having a carbon--carbon double bond in the presence of, e.g., aplatinum catalyst.

As a further example of silicone compound (B),1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane can bementioned.

Medium (C) of the crosslinking resin composition of the presentinvention is at least one compound selected from the group consisting ofwater and an organic solvent.

When a carboxyl group-containing resin as such is used as component (A),it is preferred to use an organic solvent solely as medium (C).

When a resin obtained by neutralizing a carboxylic group-containingresin with an amine compound is used as component (A), component (C) maybe a medium comprised mainly of water, and the resultant crosslinkingresin composition can be advantageously used as an aqueous crosslinkingresin composition. When a medium comprised mainly of water, which alsocontains an organic solvent, is used as component (C), it is preferredthat the weight ratio of the water to the organic solvent be in therange of from 100/0 to 50/50.

With respect to the type of the organic solvent as medium (C), there isno particular limitation, and a conventional organic solvent can beused. An organic solvent which has been used in synthesizing component(A) or component (B), as such, may be used as component (C). Forexample, a reaction mixture obtained by the synthesis of component (A),containing an organic solvent and component (A), as such, may be used asa mixture of components (A) and (C) as long as the use of such a mixtureposes no particular problem in practice. The organic solvent ascomponent (C) may be a mixed solvent. When a mixed organic solvent isused, it may be a mixture of a good solvent having a high dissolvingability for component (A) or component (B) and a poor solvent having alow dissolving ability for component (A) or component (B). When thecrosslinking resin composition of the present invention is used as acoating material and a solvent having a boiling point of less than 120°C. is used solely as medium (C), it becomes difficult to obtain acoating having a smooth surface because of the high volatility of thesolvent. On the other hand, when a solvent having a boiling point of120° C. or more is used solely as medium (C), a problem is likely tooccur in that a coating obtained from the resin composition has lowdryability because of the low volatility of the solvent. From theviewpoint of achieving both good dryability and good properties of anultimate coating, it is preferred that medium (C) be a mixture of asolvent having a boiling point of less than 120° C. and a solvent havinga boiling point of 120° C. or more.

Examples of solvents having a boiling point of less than 120° C. includeethanol, propanol, butanol, dioxane, acetone, methyl ethyl ketone,methyl propyl ketone, diethyl ketone, methyl isobutyl ketone, methylacetate, ethyl acetate, propyl acetate, isobutyl acetate, sec-butylacetate, methyl propionate, ethyl propionate, hexane, heptane, benzene,toluene and cyclohexane.

Examples of solvents having a boiling point of 120° C. or more includeisopentanol, hexanol, methylamyl alcohol, 2-ethylbutanol, cyclohexanol,methyl-n-butyl ketone, ethyl butyl ketone, dibutyl ketone,cyclohexanone, n-butyl acetate, amyl acetate, hexyl acetate, cyclohexylacetate, n-octane, xylene, ethylbenzene, trimethylbenzene, n-butylpropionate, isoamyl propionate, butyl cellosolve, propylene glycol,ethylene glycol, methyl cellosolve, ethylene glycol dimethyl ether,ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethyleneglycol dibutyl ether, diethylene glycol dimethyl ether, diethyleneglycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycolmonobutyl ether, ethylene glycol monoethyl acetate, diethylene glycolmonomethyl ether, diethylene glycol monoethyl ether, ethylene glycolmonoacetate, ethylene glycol diacetate, propylene glycol monomethylether, propylene glycol monoethyl ether, propylene glycol monopropylether, propylene glycol monobutyl ether, propylene glycol monomethylether acetate, propylene glycol dimethyl ether, propylene glycol diethylether, dipropylene glycol monomethyl ether, dipropylene glycol monoethylether, diethylene glycol monomethyl ether and diethylene glycolmonoethyl ether.

As mentioned above, when the medium comprised mainly of water is used, aresin obtained by neutralizing a carboxyl group-containing resin with anamine is used as component (A) in the aqueous crosslinking resincomposition. When a carboxyl group (carboxylic acid group)-containingresin which is not neutralized with an amine is used as component (A),problems may arise in that some carboxyl group-containing resin used ascomponent (A) have less compatibility with silicone compound (B) andthat some silicone compounds (B), which are compatible with thecarboxyl-containing resins, have poor solubility in water. By contrast,when a carboxyl group-containing resin which is neutralized with anamine is used as component (A) in combination with medium (C) comprisedmainly of water, a uniform cured resin can be easily obtained. Further,in this case, the crosslinking resin composition obtained by mixingcomponent (A), component (B) and component (C) provides a satisfactorilylong period of time for which it can be used as a coating composition.

In the aqueous crosslinking resin composition of the present invention,the carboxyl group-containing resin component (A) has no alkoxysilylgroup having high hydrolyzability, so that resin (A) has good stability,even when an aqueous medium is used as component (C). Further, sincecomponent (B) is a silicone compound, a cured resin obtained by across-linking reaction between component (A) and component (B) exhibitsadvantageous features which are characteristic of a cured siliconestructure-containing resin. Furthermore, the aqueous crosslinking resincomposition has various advantages derived from the fact that thecomposition is in an aqueous system.

When the carboxyl group-containing resin is neutralized with an amine,it is preferred that the amine be used in an amount equivalent to theamount of the carboxyl groups. However, the amount of the amine may be alittle more than or a little less than the amount equivalent to theamount of the carboxyl groups, as long as the neutralized carboxylgroup-containing resin component (A) has satisfactory solubility ordispersibility in water.

Examples of amine compounds, which can be used for neutralizing thecarboxyl group-containing resin so as to achieve a good solubilityand/or a good dispersibility in an aqueous medium, include ammonia,alkylamines and alkanolamines.

Examples of alkylamines include primary amines, secondary amines,tertiary amines and tetraalkylammonium hydroxides.

Examples of alkylamines include dimethylamine, trimethylamine,ethylamine, diethylamine, triethylamine, propylamine, isopropylamine,dipropylamine, diisopropylamine, tripropylamine, butylamine,isobutylamine, dibutylamine, diisobutylamine, tributylamine, pyridine,pentylamine, tripentylamine, N,N-dimethylaniline, cyclohexylamine,dicyclohexylamine, piperidine, picoline, morpholine, N-ethylmorpholine,diethylenetriamine, N,N-dimethylbenzylamine, tetramethylammoniumhydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxideand tetrabutylammonium hydroxide. Among these alkylamines, tertiaryamines, such as triethylamine, tripropylamine, tributylamine andN-ethylmorpholine are preferred.

Various alkanolamines may be used in the present invention. Examples ofalkanolamines include 2-aminoethanol, 3-aminopropanol,2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, diethanolamine,N-butyldiethanolamine, tripropanolamine, 1-diethylamino-2-propanol and3-(dimethylamino)-1-propanol. Among these alkanolamines,dialkylalkanolamines, such as 2-(dimethylamino)ethanol,1-diethylamino-2-propanol and 3-(dimethylamino)-1-propanol, arepreferred.

When the acid value of carboxyl group-containing resin (A) is less than10 mg KOH/g, the solubility and/or dispersibility of the carboxylgroup-containing resin cannot be satisfactorily improved even when theresin is neutralized with an amine and it becomes necessary to use alarge amount of an organic solvent. Therefore, it is preferred that theacid value of resin (A) be 10 mg KOH/g or more. If desired for furtherimproving the dispersibility of the resin (A) in water, a surfactant maybe added.

The neutralization of a carboxylic acid group-containing resin with anamine for preparing a carboxyl group-containing resin (A), which hasgood solubility and/or good dispersibility in an aqueous medium, can beperformed by a conventional method. For example, the above-mentionedneutralization can be conducted by a method in which a reaction mixture,which is obtained by the polymerization for producing the carboxylicacid group-containing resin, is subjected to removal of a polymerizationsolvent by concentration to obtain a polymer; the obtained polymer isheated in a highly water-soluble solvent, such as isopropanol,isobutanol, butyl cellosolve or diethylene glycohol dimethylether, todissolve the polymer therein; and the resultant solution of the polymerin the solvent is neutralized using an aqueous solution of an aminecompound to obtain a neutralized polymer in an aqueous form. When thepolymerization solvent used in the production of the carboxylic acidgroup-containing resin is a highly water-soluble solvent, it is possibleto use the obtained resin as such, or it is possible to remove a part ofthe solvent and neutralize the polymer with an aqueous solution of anamine compound to obtain a neutralized polymer in an aqueous form.

In the crosslinking resin composition of the present invention, theweight ratio between carboxyl group-containing resin (A) and siliconecompound (B) is not specifically limited. Silicone compound (B) may bemixed with carboxyl group-containing resin (A) in a weight ratio suchthat the epoxy groups of silicone compound (B) are present in asufficient amount to react with all of the functional groups A of resin(A), thereby achieving a satisfactory curing. When the amount ofsilicone compound (B) is less than 1 part by weight, relative to 100parts by weight of resin (A), a satisfactory curing of the crosslinkingresin composition cannot be achieved, so that an ultimate cured resinhas poor weatherability. When the amount of silicone compound (B) is 100parts by weight or more, relative to 100 parts by weight of resin (A),not only does the amount of epoxy groups which are useless because theydo not participate in the reaction with functional groups A of resin (A)become large, but the mechanical properties of an ultimate cured resinalso tend to be poor.

Generally, it is preferred that the amount of silicone compound (B) befrom 1 to 100 parts by weight, more preferably from 10 to 90 parts byweight, relative to 100 parts by weight of component (A).

It is preferred that the amount of medium (C) be from 10 to 80 weight %,based on the total weight of components (A),(B) and (C).

Especially when the crosslinking resin composition of the presentinvention is used as a material for coating compositions, such as apaint, the crosslinking resin composition may further comprise a lightstabilizer having a structure represented by the following formula(VIII): ##STR11## wherein each of R¹⁰ to R¹³ independently represents aC₁ -C₆ alkyl group, and R¹⁴ represents a hydrogen atom or a C₁ -C₆ alkylgroup.

Examples of commercially available light stabilizers having theabove-mentioned structure include Sanol LS-770, Sanol LS-765, SanolLS-2626, Sanol LS-1114 and Sanol LS-744 (all manufactured and sold bySankyo Co., Ltd., Japan); Chimassorb 944LD (manufactured and sold byCIBA-GEIGY, Switzerland); and Adekastab LA-57, Adekastab LA-62 andAdekastab LA-67 (all manufactured and sold by ASAHI DENKA KOGYO K. K.,Japan). These light stabilizers can be used individually or incombination. The amount of the light stabilizer is selected in the rangeof from 0.005 to 5% by weight, based on the weight of resin (A). In theproduction of the crosslinking resin composition of the presentinvention, the light stabilizer can be simply mixed with the othercomponents of the resin composition of the present invention.Alternatively, the light stabilizer may be first mixed with at least onecomponent selected from component (A) and component (B), and then all ofthe components may be mixed together.

The light stabilizer having a structure represented by formula (VIII)can also be used in a form such that the light stabilizer is bonded tocarboxyl group-containing resin (A).

For example, when component (A) is an acrylic resin, the binding of thelight stabilizer to the acrylic resin can be performed by a method inwhich component (A) is produced by polymerizing a mixture of a monomerfor producing component (A) with a light stabilizer monomer. Examples ofsuch light stabilizer monomers include1,2,2,6,6-pentamethyl-4-piperidyl(meth)acrylate,2,2,6,6-tetramethyl-4-piperidyl(meth)acrylate,4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine and4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine. The amount of thelight stabilizer monomer is selected in the range of from 0.005% to 5%by weight, based on the total weight of all monomers.

As mentioned above, silicon compound (B) is used as a curing agent forthe carboxylic acid group-containing resin.

For curing the crosslinking resin composition of the present invention,a curing catalyst may be used. It is preferred that the curing catalystbe at least one compound selected from the group consisting of ammonia,an amine compound, a phosphonium compound, a phosphine compound, aquaternary ammonium salt compound, an organometallic compound and a BF₃complex. Examples of curing catalysts include amine compounds, such astriethylamine, tributylamine, 2-dimethylethanolamine, 2-methylimidazole,triethylenediamine, N,N-dimethylbenzylamine, 1,5-diazabicyclo4.3.0!-nonene-5-ene and N-methylmorpholine; phosphonium compounds, suchas tetra-n-butylphosphonium chloride, tetra-n-butylphosphonium bromide,benzyltriphenylphosphonium chloride, methyltriphenylphosphonium iodideand n-amylphosphonium bromide; quaternary ammonium salt compounds, suchas tetrabutylammonium acetate, triethylbenzylammonium bromide,tetraethylammonium chloride and tetrabutylammonium bromide; phosphinecompounds, such as tri-n-butylphosphine, tri-n-octylphosphine andtriphenylphosphine; organometallic compounds, such astris(acetylacetonato)aluminum and aluminum isopropoxide; BF₃ complexes,such as BF₃ -ether complexes and BF₃ -amine complexes;3-aminopropyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; ammonia; andtetramethylammonium hydroxide.

When the crosslinking resin composition of the present invention is anaqueous crosslinking resin composition which contains as component (C) amedium composed mainly of water, in the production of the aqueouscrosslinking resin composition, ammonia, amine or the like, are used forneutralizing the carboxyl group contained in component (A). In thiscase, the ammonia, amine or the like used for the neutralization can beutilized as a catalyst for promoting the cross-linking reaction.Therefore, unless it is especially desired to use an additional curingcatalyst, incorporation of an additional curing catalyst can be omitted.However, if desired, the above-mentioned curing catalysts can beseparately added. The above-mentioned curing catalysts can be usedindividually or in combination. The amount of the curing catalyst isselected in the range of from 0.05 to 5% by weight, based on the weightof resin (A).

When the catalyst is added immediately before use of the crosslinkingresin composition, it is preferred that the catalyst be added to amixture of components (A) and (B). However, the entire amount of thecatalyst may be added to only one of the components (A) or (B), ordivided amounts of the catalyst may be added to both components (A) and(B), respectively.

When the catalyst is added to any of the components and the resultantmixture is stored prior to production and use of the crosslinking resincomposition, from the viewpoint of long-term storage, it is preferredthat the catalyst be added to component (A). Alternatively, components(A) and (B) may be stored in the form of a mixture thereof, and thecatalyst may be added to the mixture immediately before use of thecrosslinking resin composition.

At the time of using the crosslinking resin composition of the presentinvention, if desired, additives can be added, such as an antioxidant, aviscosity modifier, a pigment, and a metal powder, e.g., aluminum paste.The curing temperature is selected in the range of from ambienttemperature (for curing by spontaneous drying) to about 200° C. (forcuring by baking).

When the crosslinking resin composition of the present invention is usedas a coating composition, such as a paint, application of the coatingcomposition onto a substrate can be conducted using conventional meansfor application, such as spray, roller, brush or the like.

As is apparent from the above, carboxyl group-containing resin (A) ofthe crosslinking resin composition of the present invention is free ofan alkoxysilyl group which has high hydrolyzability. Therefore, thecrosslinking resin composition of the present invention has excellentstability. Further, since silicone compound (B) contains at least twoepoxy groups in one molecule thereof, which are capable of reacting withcarboxyl groups, the silicone compound has high reactivity with thecarboxyl groups of resin (A) and therefore, the crosslinking resincomposition has excellent curing properties. Furthermore, sincecomponent (B) is free of both a silanol group and a hydrolyzable silylgroup, even when the crosslinkable resin composition is contaminatedwith water, the water does not adversely affect the excellent stabilityof the crosslinking resin composition. Components (A) and (B) can beprovided as a 2-pack crosslinking resin composition in which components(A) and (B) are stored separately from each other and adapted to bemixed in use thereof.

The novel crosslinking resin composition of the present invention isstable, and a cured resin obtained by a crosslinking reaction ofcomponents (A) and (B) has excellent features which are characteristicof a cured silicone structure-containing resin, such as excellentweatherability, stain resistance and acid resistance. Therefore, thecrosslinking resin composition of the present invention is extremelyuseful as a material for coating compositions, such as a paint, asealant and the like.

PREFERRED EMBODIMENT OF THE INVENTION

Hereinbelow, the present invention is described in more detail withreference to Referential Examples, Examples and Comparative Examples,which should not be construed as limiting the scope of the presentinvention.

In the following Referential Examples, Examples and ComparativeExamples, the NMR spectrum was obtained using an NMR spectrometer,PMX60Si (manufactured and sold by JEOL Ltd., Japan), the infraredadsorption spectrum (IR) was obtained using a Fourier transform infraredspectrophotometer, FT/IR5300 (manufactured and sold by JapanSpectroscopic Co., Ltd., Japan), and the molecular weight was measuredby gel permeation chromatography (GPC).

Various properties of a cured coating were evaluated in accordance withthe following methods and evaluation criteria.

1) Appearance: evaluation was made by visually observing the curedcoating.

◯: good

Δ: slightly poor

x: poor

2) Gloss: evaluation was made in accordance with JIS K5400-7.6 (60°).

◯: 85% or more in terms of specular gloss

Δ: from 61 to 84%

x: 60% or less

3) Gel %: measured by dipping the cured coating in acetone at 20° C. for24 hours and determining and taking the residual weight ratio (%) as agel % of the coating.

4) Pencil hardness: evaluation was made in accordance with JISK5400-8.4.1 (measured by scratching the cured coating with a pencil).

5) Adhesion properties: evaluation was made in accordance with JISK5400-8.5.2.

◯: 10-8 score

Δ: 6-4 score

X: 2-0 score

6) Weatherability: evaluation was made in accordance with ASTM G-53, inwhich, upon 2,500-hour exposure, gloss retention (%) of the curedcoating was determined.

◯: 90% or more in terms of gloss retention

x: less than 90%

7) Acid resistance: evaluation was made in accordance with JISK5400-8.22.

8) Pot life: the period of time, for which a coating solution can beused, counted from the time of the preparation of the coating solution.

REFERENTIAL EXAMPLE 1

Preparation of a resin solution containing the resin component (A)!

Resin solution (A-1)

50 g of toluene and 50 g of butyl acetate as solvents were charged in a0.5-liter four-necked flask provided with a thermometer, an agitator, acooling pipe and a nitrogen gas feeding pipe. Then, a dropping funnel,in which a mixture of 68 g of methyl methacrylate, 19.5 g of n-butylacrylate, 5 g of methacrylic acid, 7.5 g of 2-hydroxyethyl methacrylate,1.5 g of azobisisobutyronitrile (hereinafter referred to simply as"AIBN") had been introduced, was attached to the above-mentionedfour-necked flask. Nitrogen gas was fed to the four-necked flask tothereby purge the flask with the nitrogen gas. Heating and stirring ofthe solvents in the flask were started. When the temperature of thesolvent mixture reached 90° C., the monomer mixture contained in thedropping funnel was added dropwise to the solvents in the flask whilemaintaining the internal temperature of the flask at 90° C., to therebyeffect a polymerization reaction. After completion of the addition,stirring was further conducted at 90° C. for 5 hours to thereby obtainresin solution (A-1).

The obtained resin solution (A-1) was analyzed by gas chromatography. Asa result, it was found that the conversion of each of the methylmethacrylate, n-butyl acrylate, methacrylic acid and 2-hydroxyethylmethacrylate was 100%.

Further, the molecular weight of the resin contained in resin solution(A-1) was measured by gel permeation chromatography (hereinafterreferred to simply as "GPC"). As a result, it was found that the resinhad a number average molecular weight (hereinafter referred to simply as"Mn") of 9,800 and a weight average molecular weight (hereinafterreferred to simply as "Mw") of 19,000. The resin had an acid value of 33mg KOH/g and a hydroxyl value of 32 mg KOH/g.

Resin solution (A-2)

In substantially the same four-necked flask as used in the preparationof resin solution (A-1) were charged 50 g of toluene and 50 g of butylacetate as solvents, and a monomer mixture having a formulation asdescribed below was added dropwise to the solvent mixture in the flaskat 90 ° C. while stirring, to thereby effect a polymerization reaction.After completion of the addition, stirring was further conducted at 90°C. for 5 hours to thereby obtain resin solution (A-2).

    ______________________________________                                        methyl methacrylate    70.0 g                                                 n-butyl acrylate       20.0 g                                                 methacrylic acid       10.0 g                                                 AIBN                   1.5 g                                                  ______________________________________                                    

The resin contained in the obtained resin solution (A-2) had an Mn of10,600 and an acid value of 64 mg KOH/g.

Resin solution (A-3)

In substantially the same four-necked flask as used in the preparationof resin solution (A-1) were charged 50 g of toluene and 50 g of butylacetate as solvents, and a monomer mixture having a formulation asdescribed below was added dropwise to the solvents in the flask at 90°C. while stirring, to thereby effect a polymerization reaction. Aftercompletion of the addition, stirring was further conducted at 90° C. for5 hours to thereby obtain resin solution (A-3).

    ______________________________________                                        methyl methacrylate     55.0 g                                                n-butyl acrylate        30.0 g                                                methacrylic acid        10.0 g                                                2-hydroxyethyl methacrylate                                                                           5.0 g                                                 AIBN                    1.5 g                                                 ______________________________________                                    

The resin contained in the obtained resin solution (A-3) had an Mn of11,700, an acid value of 64 mg KOH/g and a hydroxyl value of 22 mgKOH/g.

Resin solution (A-4)

In substantially the same four-necked flask as used in the preparationof resin solution (A-1) were charged 100 g of diethylene glycol dimethylether and 50 g of isopropanol as solvents, and a monomer mixture havinga formulation as described below was added dropwise to the solventmixture in the flask at 90° C. while stirring, to thereby effect apolymerization reaction. To the resultant reaction mixture, the mixtureof 0.17 g of AIBN and 3 g of diethylene glycol dimethyl ether wasfurther dropwise added at 90° C. while stirring. After completion of theaddition, stirring was further conducted at 90° C. for 5 hours tothereby obtain resin solution (A-4).

    ______________________________________                                        methyl methacrylate     50.2 g                                                n-butyl acrylate        29.4 g                                                cyclohexyl methacrylate 5.0 g                                                 methacrylic acid        15.4 g                                                AIBN                    3.0 g                                                 ______________________________________                                    

The resin contained in the obtained resin solution (A-4) had an Mn of10,000 and an acid value of 100 mg KOH/g.

REFERENTIAL EXAMPLE 2

Preparation of an aqueous resin solution containing a resin as component(A)!

Aqueous resin solution (A-5)

Resin solution (A-1) obtained above was added to a 5-time amount ofn-hexane to obtain a highly viscous resin solution. The obtained resinsolution was dried at 70 ° C. for 2 hours in vacuum to remove thesolvents completely, so that a solid resin was obtained. 50 g of theobtained solid resin was dissolved in 25 g of butyl cellosolve underheating. To the resultant mixture was added 150 g of an aqueous solutioncontaining 3.2 g of triethylamine, to thereby obtain aqueous resinsolution (A-5).

Aqueous resin solution (A-6)

Resin solution (A-2) obtained above was treated in substantially thesame manner as described above in connection with the preparation ofaqueous resin solution (A-5), to thereby obtain a solid resin. 50 g ofthe obtained solid resin was dissolved in 25 g of butyl cellosolve withheating. To the resultant mixture was added 125 g of an aqueous solutioncontaining 5.4 g of N,N-dimethyl ethanolamine, to thereby obtain aqueousresin solution (A-6).

REFERENCE EXAMPLE 3

Synthesis of component (B)!

Silicone compound (B-1)

In a 300-ml four-necked flask provided with a thermometer, a magneticstirrer, a cooling pipe and a nitrogen gas feeding pipe were charged0.10 g of a 8% isopropanol solution of chloroplatinic acid, 77.1 g ofallyl glycidyl ether and 15.0 g of1,3,5,7-tetramethylcyclotetrasiloxane, and a reaction was performed at100° C. for 3 hours. The resultant reaction mixture was taken out, andsubjected to distillation at a temperature of not more than about 80° C.in vacuum to remove the solvents completely. Thus, 41.9 g of a siliconecompound (B-1) having low viscosity was obtained. The obtained siliconecompound (B-1) had an Mn of 700 as measured by GPC. When the siliconecompound (B-1) was added to a 2N NaOH solution, no hydrogen gas wasgenerated, and 100% of the Si--H groups were reacted. This siliconecompound had 4 epoxy groups per molecule thereof.

Silicone compound (B-2)

(1) Synthesis of an intermediate a;

240 g of isopropyl ether and 480 g of purified water were charged in a2-liter four-necked flask provided with a thermometer, a magneticstirrer, a cooling pipe for conducting cooling with dry ice and ethanol,and a nitrogen gas feeding pipe. Stirring of the solvents in the flaskwas started. Nitrogen gas was fed to the four-necked flask to therebypurge the flask with the nitrogen gas. A dropping funnel, in which 245.6g of methyldichlorosilane had been introduced, was attached to theabove-mentioned four-necked flask. Then, the methyldichlorosilane in thedropping funnel was added dropwise to the solvent mixture in the flaskover 90 minutes, while maintaining the internal temperature of the flaskat 15° to 20° C., to thereby effect a reaction. After completion of theaddition, the resultant reaction mixture was separated into an organicphase and an aqueous phase in a separation funnel. 90 g of isopropylether was added to the separated aqueous phase to perform extraction toobtain an organic phase. The obtained organic phase was added to theorganic phase obtained by the previous extraction, and the resultantmixture was washed 3 times using about 300 ml of water. The amount ofthe organic phase obtained after the washing was 395 g. 197 g of theobtained organic phase was charged in a simple distillation apparatusfor vacuum distillation. A distillation was first performed underatmospheric pressure to remove 113 g of unreacted isopropyl ether andthen, the pressure was gradually decreased until the pressure became 2mmHg and the bottom temperature became 160° C., thereby obtaining 64.72g of a distillate containing siloxane compounds (hereinafter referred toas "intermediate a"), and 18.1 g of a residue at the bottom of thedistillation apparatus. The obtained distillate containing siloxanecompounds (intermediate a) was analyzed by gas chromatography. As aresult, it was found that the distillate (intermediate a) had a1,3,5,7-tetramethylcyclotetrasiloxane content of 37%, a1,3,5,7,9-pentamethylcyclosiloxane content of 19% and a total content ofother cyclosiloxanes having Si₆ -Si₁₂ of 15%.

(2) Synthesis of silicone compound (B-2):

In a 200-ml four-necked flask provided with a thermometer, a magneticstirrer, a cooling pipe and a dropping funnel were charged 13 mg of a 8%isopropanol solution of chloroplatinic acid and 62.3 g of allyl glycidylether, followed by stirring at 65° C. A mixture of 32.33 g of theintermediate a obtained above and 18.7 g of isopropyl ether was addeddropwise to the mixture in the flask using the dropping funnel, toeffect a reaction at 80° C. for 1 hour. The resultant reaction mixturewas taken out, and subjected to distillation at a temperature of notmore than about 80° C. in vacuum to remove the solvents completely.Thus, 64.5 g of a silicone compound (B-2) having low viscosity wasobtained. The obtained silicone compound (B-2) had an Mn of 720 asmeasured by GPC. When the silicone compound (B-2) was added to a 2N NaOHsolution, no hydrogen gas was generated, and 100% of the Si--H groupswere reacted. From the Mn value, it was determined that this siliconecompound had about 4.1 epoxy groups on the average per molecule thereof.

Silicone compound (B-3)

In a 300-ml four-necked flask provided with a thermometer, a magneticstirrer, a cooling pipe and a nitrogen gas feeding pipe were charged 12mg of a 8% isopropanol solution of chloroplatinic acid, 60.0 g of5-epoxy-1-hexene and 52.0 g of isopropyl ether. 24.6 g of1,3,5,7-tetramethylcyclotetrasiloxane was added dropwise to the mixturein the flask at 65° C., and a reaction was performed at 80° C. for 1hour. The resultant reaction mixture was treated in substantially thesame manner as described above in connection with the preparation ofsilicone compound (B-2), to thereby obtain 63.0 g of a silicone compound(B-3) having low viscosity. This silicone compound had 4 epoxy groupsper molecule thereof.

Silicone compounds (B-4) and (B-5)

(1) Synthesis of intermediates b and c:

In a 300-ml four-necked flask provided with a thermometer, a magneticstirrer and a cooling pipe were charged 100 g of1,3,5,7-tetramethylcyclotetrasiloxane, 100 g of hexamethyldisiloxane and1.3 g of sulfuric acid, and a reaction was performed at 20° C. for 2hours while stirring. The resultant reaction mixture was washed withwater, using a separation funnel, until the washings became neutral. Theresultant organic phase was purified by repeatedly performing a vacuumdistillation, thereby obtaining straight chain siloxane compounds(intermediate b and c) represented by the following formula:

    Me.sub.3 Si--O--(MeHSiO).sub.p --SiMe.sub.3

wherein p represents an integer of 4 for the intermediate b and aninteger of 5 for the intermediate c.

(2) Synthesis of silicone compound (B-4):

In a 100-ml four-necked flask provided with a thermometer, a magneticstirrer, a cooling pipe and a nitrogen gas feeding pipe were charged 9mg of a 8% isopropanol solution of chloroplatinic acid and 40.0 gvinylcyclohexene oxide as solvents. A mixture of 13.0 g of theintermediate b obtained above and 13.0 g of isopropyl ether was addeddropwise to the solvent mixture in the flask at 65° C., and a reactionwas performed at 80° C. for 1 hour. The resultant reaction mixture wastreated in substantially the same manner as described above inconnection with the preparation of silicone compound (B-3), to therebyobtain 30 g of silicone compound (B-4) having low viscosity. Thissilicone compound had 4 epoxy groups per molecule thereof.

(3) Synthesis of silicone compound (B-5):

In a 100-ml four-necked flask provided with a thermometer, a magneticstirrer, a cooling pipe and a nitrogen gas feeding pipe were charged 9mg of a 8% isopropanol solution of chloroplatinic acid, and 40.0 g allylglycidyl ether and 13.3 g of toluene. 13.1 g of the intermediate c wasadded dropwise to the mixture in the flask at 65° C., and a reaction wasconducted at 80° C. for 1 hour. The resultant reaction mixture wastreated in substantially the same manner as described above inconnection with silicone compound (B-3), to thereby obtain 30 g ofsilicone compound (B-5) having low viscosity. This silicone compound had5 epoxy groups per molecule thereof.

REFERENCE EXAMPLE 4

Synthesis of comparative compounds!

Comparative resin solution (A-1)

As a comparative compound, a vinyl copolymer having alkoxysilyl groupswas synthesized by the following method.

In substantially the same four-necked flask as used in the preparationof resin solution (A-1) were charged 50 g of toluene and 50 g of butylacetate as solvents, and a monomer mixture having a formulation asdescribed below was added dropwise to the solvent mixture at 90° C.while stirring, to thereby effect a polymerization reaction. Aftercompletion of the addition, stirring was further conducted at 90° C. for5 hours to thereby obtain a vinyl copolymer as comparative resinsolution (A-1).

    ______________________________________                                        methyl methacrylate    51.0 g                                                 n-butyl acrylate       28.0 g                                                 methacrylic acid       4.0 g                                                  3-methacryloxypropyl-  17.0 g                                                 trimethoxysilane                                                              AIBN                   1.5 g                                                  ______________________________________                                    

Comparative silicone compound (B-1)

In a 1-liter four-necked flask provided with a thermometer, a magneticstirrer and a cooling pipe were charged 6.8 g of methyltrimethoxysilane,236.2 g of 3-glycidoxypropyltrimethoxysilane, 60.0 g of water, 2 g of a3% hydrochloric acid solution and 300 g of metha- nol, and a reactionwas conducted at 60° C. for 2 hours. The resultant reaction mixture wastaken out, and subjected to distillation at 60° C. in vacuum to therebyremove the solvents completely. Thus, a silicone compound comparativesilicone compound (B-1)! comprising a hydrolyzable silyl group (Si--OMe,wherein `Me` means a methyl group) was obtained. The obtained siliconecompound had an Mn of 1,700 as measured by GPC. When the siliconecompound was stored at room temperature for about 2 months, it wasobserved that the silicone compound was in the state of a gel and wasinsoluble in an organic solvent, such as acetone.

Example 1

100 parts by weight of the resin solutions (A-1) to (A-3) (50 parts byweight in terms of the resin) as component (A) were individually blendedwith 10 parts by weight of each of the silicone compounds (B-1) to (B-5)as component (B), to thereby obtain resin mixtures, and water was addedto each of the resin mixtures in an amount of 6,000 ppm by weight, basedon the weight of the each resin mixture. The resultant mixtures werestored at room temperature for 1 month. After that period of time, eachof the mixtures was observed with respect to the change of viscosity. Nomarked increase in viscosity was observed.

Comparative Example 1

Substantially the same procedure as in Example 1 was repeated, exceptthat the resin solution comparative resin solution (A-1)! was usedinstead of the resin solution (A-1). The mixtures obtained by blendingcomponent (B) underwent gellation within one month.

Examples 2 to 11

A resin solution selected from (A-1) to (A-4) as component (A), asilicone compound selected from (B-1) to (B-5) as component (B), acuring catalyst selected from catalysts a to g (a: tetrabutylammoniumacetate, b: N,N-dimethylbenzylamine, c: tetrabutylphosphonium chloride,d: triphenylphosphine, e: aluminum acetylacetonate, g: triethylamine)and SANOL LS-765 (a light stabilizer, manufactured and sold by SankyoCorporation Limited, Japan) were blended in the respective amountsindicated in Table 1, to thereby obtain coating compositions. Theviscosity of the obtained coating composition was adjusted to a value of15 seconds of Ford viscosity cup No. 4 (ASTM D-1200) using, as athinner, a solution obtained by mixing toluene, butyl acetate anddiethylene glycol dimethyl ether in the weight ratio of 5:5:1. Theresultant coating composition was coated. The coating was cured by heatat 120 ° C. for 30 minutes. The obtained cured coating was evaluated.Results are shown in Table 2.

Comparative Examples 2 to 4

A resin solution selected from (A-1) and (A-4) as component (A), asilicone compound selected from comparative silicone compound (B-1) and2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane (hereinafter referred to asECTMS) as component (B) were blended in the amounts indicated in Table1, to thereby obtain coating compositions. The coating composition wastreated in the same manner as in Example 2. The obtained cured coatingwas evaluated. Results are shown in Table 2.

                                      TABLE 1                                     __________________________________________________________________________                                 Comparative                                                                   Example Nos. and                                         Example Nos. and Amounts of Components                                                             Amounts of Components                                    (parts by weight)    (parts by weight)                                Components                                                                            2 3 4 5 6 7 8 9 10                                                                              11 2   3  4                                         __________________________________________________________________________    (1)                                                                             A-1     80              87 80     80                                        (2)                                                                             A-2   80  80    80                                                          (3)                                                                             A-3         80    80                                                                              80                                                                              80       80                                           (4)                                                                             A-4           75                                                              B-1   20                                                                              20                                                                              20                                                                              20                                                                              25                                                              B-2             20      13                                                    B-3               20                                                          B-4                 20                                                        B-5                   20                                                    Comparartive B-1             20  20                                           ECTMS                               20                                        Catalyst a                                                                              2       2 2   2                                                     Catalyst b  2         2             2                                         Catalyst c    2                                                               Catalyst d                                                                            2       2                                                             Catalyst e                   2   2                                            Catalyst g                3                                                   SANOL LS-765              0.1                                                 __________________________________________________________________________     Note; as for (1) to (4), the amount of Component indicates the amount of      the solid contained therein.                                             

                                      TABLE 2                                     __________________________________________________________________________                                 Comparative                                                                   Example Nos. and                                 Properties of                                                                          Example Nos. and Results of Evaluation                                                            Results of Evaluation                            cured Coatings                                                                         2 3 4 5 6 7 8 9 10                                                                              11                                                                              2  3   4                                         __________________________________________________________________________    Appearance                                                                             ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   x  x   ∘                             Gloss    ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   x  x   ∘                             Gel %    98                                                                              94                                                                              96                                                                              97                                                                              98                                                                              96                                                                              97                                                                              92                                                                              94                                                                              95                                                                              50 30  74                                        Pencil hardness                                                                        2H                                                                              H 2H                                                                              2H                                                                              2H                                                                              H 2H                                                                              HB                                                                              H F B  2B  H                                         Adhesiveness                                                                           ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                    ∘                                                                     ∘                             Weatherability                                                                         ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   x  x   x                                         Acid Resistance                                                                        ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   ∘                                                                   Δ                                                                          Δ                                                                           ∘                             __________________________________________________________________________

Examples 12 to 13

To 500 parts by weight of n-hexane were added 100 parts by weight of aresin solution (A-2) as component (A). The obtained solid was dried invacuuo at 100° C. for 2 hours, to thereby remove the solvent. Thus, asolid resin of (A-2) freed of solvent was obtained. The obtained solidresin as component (A), silicone compound (B-3) as component (B),N,N-dimethylbenzylamine as a curing catalyst, and solvents (T: toluene,I: isopropanol, BuA: n-butyl acetate, DG: diethyleneglycoldimethylether) were used in the respective amounts indicated in Table 3to prepare coating compositions. The prepared coating composition wascoated, and then, cured by heat at 120° C. for 30 minutes. The obtainedcured coating was evaluated. Results are shown in Table 3.

Examples 14 to 15

Example 12 and 13 were repeated except that only-one-type of organicsolvent was used. The obtained cured coating was evaluated. Results areshown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________           Amount of                                                                     Component (A)                                                                        Amount of                                                                            Amount of                                                                            Amount of                                                                          Amount of                                                                          Amount of                                                                           Amount of                         Example Nos.                                                                         (Solid Resin)                                                                        Component (B)                                                                        Curing Catalyst                                                                      Solvent T                                                                          Solvent I                                                                          Solvent BuA                                                                         Solvent DG                                                                          Appearance                                                                          Gloss                                                                            Gel                __________________________________________________________________________                                                               %                  Example 12                                                                           80 parts                                                                             20 parts                                                                             2 parts                                                                              100 parts                                                                          0 part                                                                             100 parts                                                                           100 parts                                                                           ∘                                                                       ∘                                                                    97                 Example 13                                                                           75 parts                                                                             25 parts                                                                             2 parts                                                                              100 parts                                                                          50 parts.sup.                                                                       50 parts                                                                           100 parts                                                                           ∘                                                                       ∘                                                                    97                 Example 14                                                                           80 parts                                                                             20 parts                                                                             2 parts                                                                              300 parts                                                                          0 part                                                                             .sup. 0 part                                                                        .sup. 0 part                                                                        ∘                                                                       on 90                 Example 15                                                                           75 parts                                                                             25 parts                                                                             2 parts                                                                               .sup. 0 part                                                                      0 part                                                                             300 parts                                                                           .sup. 0 part                                                                        ∘                                                                       on 95                 __________________________________________________________________________

Examples 16 to 20

80 parts by weight of resin solution (A-2) as component (A), based onthe weight of the solid resin, 20 parts by weight of silicone compound(B-1) as a component (B) and 2% by weight of curing catalysts (a:tetrabutylammonium acetate, b: N,N-dimethylbenzylamine, c:tetrabutylphosphonium chloride, d: tri-phenylphosphine, f: tetramethylammoniumhydroxyde) relative to the weight of the solid contained incomponents (A) and (B) were blended, to thereby obtain a coatingcomposition. The viscosity of the obtained coating composition wasadjusted to a value of 15 seconds of Ford viscosity cup No. 4, using, asa thinner, a solution obtained by mixing toluene, butyl acetate anddiethylene glycol dimethyl ether in the weight ratio of 5:5:1. Theobtained coating composition was coated, and then, cured at roomtemperature for 7 days or 14 days. The obtained cured coating wasevaluated. Results are shown in Table 4.

                  TABLE 4                                                         ______________________________________                                               Com-              Curing                                               Example                                                                              ponent  Component Cata- Appea-                                                                              Gel %                                    Nos.   (A)     (B)       lyst  rance 7 days                                                                              14 days                            ______________________________________                                        Example                                                                              A-2     B-3       a     o     94    96                                 16                                                                            Example                                                                              A-2     B-3       b     o     92    95                                 17                                                                            Example                                                                              A-2     B-3       c     o     93    96                                 18                                                                            Example                                                                              A-2     B-3       d     o     88    93                                 19                                                                            Example                                                                              A-2     B-3       f     o     93    95                                 20                                                                            ______________________________________                                    

Examples 21 to 23

A resin solution selected from (A-5) and (A-6) as component (A), asilicone compound selected from (B-1) and (B-2) as component (B) and alight stabilizer, SANOL LS-765 were blended in the amounts indicated inTable 5, to thereby prepare coating compositions. The prepared coatingcomposition was coated using an applicator, to thereby obtain a coating.The obtained coating was allowed to stand at room temperature for 1hour, and then, cured by heat at 120° C. for 30 minutes. The obtainedcured coating was evaluated. Results are shown in Table 6.

                  TABLE 5                                                         ______________________________________                                                  Example Nos. and Amount of                                                    Components (parts by weight)                                        Components  21          22       23                                           ______________________________________                                        A-5                              83                                           A-6         80          90                                                    B-1         20                   17                                           B-2                     10                                                    GPTMS                                                                         Stannous Catalyst                                                             Almina Catalyst                                                               Purified Water                                                                SANOL LS-765            0.1                                                   ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                                    Example Nos. and Results of                                       Properties of                                                                             Evaluation                                                        Cured Coatings                                                                            21          22       23                                           ______________________________________                                        Appearance  0           0        0                                            Gloss       0           0        0                                            Gel %       93          93       94                                           Pencil hardness                                                                           2H          H        H                                            Adhesiveness                                                                              0           0        0                                            Weatherability                                                                            0           0        0                                            Acid Resistance                                                                           0           0        0                                            Pot life (hr)                                                                             5<          5<       5<                                           ______________________________________                                    

Industrial Applicability

The crosslinking resin composition of the present invention not onlyexhibits excellent storage stability, but is also capable of providing,upon being crosslinked, a cured resin having excellent gloss,weather-ability, acid resistance, solvent resistance, water repellencyand stain resistance. Therefore, the cross-linking resin composition ofthe present invention can be advantageously used as a material forproviding coating compositions, such as paints, sealants and the like,especially for providing a high performance coating composition to beused as, for example, a topcoating and an intercoating material for usein production of an automobile, a coating material for repairing anautomobile, a coating material for architectures, a coating material fora building material, a coating material for plastics and a coatingmaterial for various metallic products.

We claim:
 1. A crosslinking resin composition comprising:(A) a carboxylgroup-containing resin having a number average molecular weight of from1,000 to 40,000 g/mole and an acid value of from 10 to 400 mg KOH/g; (B)a cyclic or chain silicone compound as a curing agent, having a numberaverage molecular weight of from 350 to 8,000 g/mole and containing atleast two epoxy groups in one molecule thereof, wherein said siliconecompound is free of a silanol group, a hydrolyzable silyl group or avinyl polymer structure, and wherein said silicone compound has a siloxygroup-containing skeleton represented by a formula selected from thegroup consisting of the following formulae (I) and (II): ##STR12##wherein n is an integer of from 3 to 20, and ##STR13## (C) a mediumselected from the group consisting of water and an organic solvent. 2.The crosslinking resin composition according to claim 1, wherein saidcarboxyl group-containing resin (A) is at least one resin selected fromthe group consisting of an acrylic resin, a polyester resin and afluorine-containing resin.
 3. The crosslinking resin compositionaccording to any one of claims 1 or 2, wherein said silicone compound(B) has no functional groups capable of reacting with a carboxyl groupother than said epoxy groups.
 4. The crosslinking resin compositionaccording to claim 3, wherein said silicone compound (B) is at least onesilicone compound selected from the group consisting of a cyclicsilicone compound represented by the following formula (III): ##STR14##wherein m is an integer of from 3 to 16, each R¹ independentlyrepresents a C₁ -C₁₀ alkyl group and each Ep independently represents agroup represented by a formula selected from the group consisting of thefollowing formulae (1), (2) and (3): ##STR15## wherein j is an integerof from 2 to 6; and a chain silicone compound represented by thefollowing formula (IV): ##STR16## wherein each of R² to R⁸ independentlyrepresents a C₁ -C₁₀ alkyl group, each Ep is as defined above forformula (III) and r is an integer of from 3 to
 16. 5. The crosslinkingresin composition according to claim 1, wherein said silicone compound(B) is obtained by a hydrosilylation reaction of a Si--H-containingsilane compound with an epoxy group-containing compound having acarbon-carbon double bond, said Si--H-containing silane compound beingrepresented by a formula selected from the group consisting of thefollowing formulae (V), (VI) and (VII): ##STR17## wherein each Yindependently represents a hydrogen atom or a C₁ -C₁₀ alkyl group, withthe proviso that at least two Ys in one molecule of the Si--H-containingsilane compound are hydrogen atoms, and q is an integer of from 2 to 10;##STR18## wherein each Y independently represents a hydrogen atom or aC₁ -C₁₀ alkyl group, with the proviso that at least two Ys in onemolecule of the Si--H-containing silane compound are hydrogen atoms, andp is an integer of from 3 to 20; and ##STR19## wherein each Yindependently represents a hydrogen atom or a C₁ -C₁₀ alkyl group, withthe proviso that at least two Ys in one molecule of the Si--H-containingsilane compound are hydrogen atoms, and s is an integer of from 3 to 16.6. The crosslinking resin composition according to any one of claims 1or 2, which further comprises a curing catalyst.
 7. The crosslinkingresin composition according to claim 6, wherein said curing catalyst isat least one compound selected from the group consisting of ammonia, anamine compound, a phosphonium compound, a phosphine compound, aquaternary ammonium salt compound, an organometallic compound and a BF₃complex.
 8. The crosslinking resin composition according to any one ofclaims 1 or 2, which further comprises a light stabilizer containing astructure represented by the following formula (VIII): ##STR20## whereineach of R¹⁰ to R¹³ independently represents a C₁ -C₆ alkyl group, andR¹⁴ represents a hydrogen atom or a C₁ -C₆ alkyl group.
 9. A method forcuring a carboxyl group-containing resin, which comprises reacting acarboxyl group-containing resin having a number average molecular weightof from 1,000 to 40,000 g/mole and an acid value of from 10 to 400 mgKOH/g with a cyclic or chain silicone compound having a number averagemolecular weight of from 350 to 8,000 g/mole and containing at least twoepoxy groups in one molecule thereof, wherein said silicone compound isfree of a silanol group, a hydrolyzable silyl group or a vinyl polymerstructure, and wherein said silicone compound is at least one siliconecompound selected from the group consisting of the following compounds(1) to (4):(1) a cyclic silicone compound represented by the followingformula (III): ##STR21## wherein m is an integer of from 3 to 16, eachR¹ independently represents a C₁ -C₁₀ alkyl group and each Epindependently represents a group represented by a formula selected fromthe group consisting of the following formulae (1), (2) and (3):##STR22## wherein j is an integer of from 2 to 6, (2) a chain siliconecompound represented by the following formula (IV): ##STR23## whereineach of R² to R⁸ independently represents a C₁ -C₁₀ alkyl group, each Epis as defined above for formula (III) and r is an integer of from 3 to16, (3) a silicone compound obtained by a hydrosilylation reaction of aSi--H-containing silane compound with an epoxy group-containing compoundhaving a carbon-carbon double bond, said Si--H-containing silanecompound being represented by a formula selected from the groupconsisting of the following formulae (V), (VI) and (VII): ##STR24##wherein each Y independently represents a hydrogen atom or a C₁ -C₁₀alkyl group, with the proviso that at least two Ys in one molecule ofthe Si--H-containing silane compound are hydrogen atoms, and q is aninteger of from 2 to 10; ##STR25## wherein each Y independentlyrepresents a hydrogen atom or a C₁ -C₁₀ alkyl group, with the provisothat at least two Ys in one molecule of the Si--H-containing silanecompound are hydrogen atoms, and p is an integer of from 3 to 20; and##STR26## wherein each Y independently represents a hydrogen atom or aC₁ -C₁₀ alkyl group, with the proviso that at least two Ys in onemolecule of the Si--H-containing silane compound are hydrogen atoms, ands is an integer of from 3 to 16, and (4)1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane.
 10. Thecrosslinking resin composition according to any one of claims 1 or 2,wherein said carbonyl group-containing resin (A) has a stabilizer bondedthereto, said stabilizer containing a structure represented by thefollowing formula (VIII): ##STR27## wherein each of R¹⁰ to R¹³independently represents a C₁ -C₆ alkyl group, and R¹⁴ represents ahydrogen atom or a C₁ -C₆ alkyl group.